28-12-2007 22:52

Éowyn

Re: pic: Front / Rear bearing saddles rev 2

That looks fairly similar to a globe motor mount I made last year. Those little holes were a real pain in the drain to line up.

29-12-2007 23:47

robostangs548

Re: pic: Front / Rear bearing saddles rev 2

nice!

30-12-2007 06:30

Richard McClellan

Re: pic: Front / Rear bearing saddles rev 2

So are you machining that out of a solid piece of aluminum or are you just going to bend some 5052 or 3003?

30-12-2007 13:06

Andrew Schuetze

Re: pic: Front / Rear bearing saddles rev 2

I am open to suggestions and we in fact are very much dependant upon a machine shop to help us with this project. I don't have any experience bending anything other than sheet metal. Does one need a hydraulic bender to make the 90 degree bends in the 5/16" aluminum?

30-12-2007 13:08

Andrew Schuetze

Re: pic: Front / Rear bearing saddles rev 2

Those little holes are actually tapped for a machine screw and washer. The intent is that they will capture the flanged ball bearing. I uploaded the wrong file. The final version has a 0.500 inch fillet to round off the corners on the bottom.

30-12-2007 13:11

Cory

Re: pic: Front / Rear bearing saddles rev 2

Absolutely. I've never bent anything near that thick, but there's no way you're going to be able to do it with a hand break.

30-12-2007 16:38

artdutra04

Re: pic: Front / Rear bearing saddles rev 2

You aren't really going to be able to bend 5/16" thick aluminum with a radius small enough to satisfy your demands. Generally when working with sheet metal, the bend radius should be at least the thickness of the material, and can actually be a lot greater depending on the alloy.

Also, what types of machines would your machine shop be able to provide?

The types of machines they have can greatly affect how you design your parts; if they had a sheet metal turret/punch or a waterjet, you could design that entire bracket to size out of 0.1875" or 0.125" aluminum and have it bent to 90º. Then to increase the thickness needed for a flush bearing fit, you can just make a second small plate that goes around the bearing hole and is bolted to the main bracket.

But if they have conventional milling machines, it's hard to find extruded aluminum in fractional sizes above about 2.00", so they'd have to mill it out of a solid block of aluminum, which would drive costs up if it's not being donated to your team.

30-12-2007 17:23

=Martin=Taylor=

Re: pic: Front / Rear bearing saddles rev 2

You could always do it with a blow torch , It can be hard to get it accurate but it's a lot of fun. So long as you make it hug the frame member tight, you can then go back and cut the bearing holes to fit.

30-12-2007 18:15

Andrew Schuetze

Re: pic: Front / Rear bearing saddles rev 2

Now that I have my design,

To make machining easier, what if I made this a three piece bolt together assembly? It would have two identical side plates and then the top piece. Maybe four tapped holes for #8 or #10 machine screws or clearance holes for the same with nylon lock nuts at the end of 2" bolts... I wouldn't know how to calculate the bolt strength needed to deal with the loads.

30-12-2007 18:40

artdutra04

Re: pic: Front / Rear bearing saddles rev 2

Does your machine shop have welding capabilities?

When my father and myself were working on the Mountain Dewbot, we machined a bunch of brackets similar to the one in this thread out of 0.25" aluminum plate, tapped and threaded for 6-32 hardware to hold it square, and had the seams welded. As long as you bevel the edges (after tapping) where they'll weld, you'll get good penetration and have a strong joint.

30-12-2007 18:56

Andrew Schuetze

Re: pic: Front / Rear bearing saddles rev 2

I like this idea. Since I don't have clearance for welded material on the inside seams you are suggesting that we chamfer the edges that will butt together so that the weld will have a void to fill and hold it together.

30-12-2007 21:24

Cory

Re: pic: Front / Rear bearing saddles rev 2

Make sure that if you make it out of more than one piece, you put the motor and bearings in first, and align everything as it should be prior to welding.

Screws are not good for holding locations. You will have enough play in your pieces that if you don't get everything lined up, you could easily end up with your bores not being concentric after welding.

30-12-2007 21:31

artdutra04

Re: pic: Front / Rear bearing saddles rev 2

Yes. The chamsfer will help the weld penetrate deeper into the material for a stronger hold, and it will end up being nearly flush. (Since the edges of the 80/20 extrusion are rounded, there is a slight tolerance there anyway. )

Here's a picture of the brackets from the Dewbot that I mentioned in my previous post.

31-12-2007 10:57

Andy Brockway

Re: pic: Front / Rear bearing saddles rev 2

Another alternative is to weld the three pieces first and then do all your machining. This allows any warpage or misalignment to be machinined out of the bracket. Decide on your main datum plane and dimension off this for the machining.